Digital versatile discs (DVDs) are information storage devices used for storing prerecorded audio information, movies and computer software. The storage mechanism used in DVDs closely resembles that used in compact discs (CDs). DVD players also use the same laser technology as CD players. Briefly, both DVDs and CDs store information as a pattern of pits formed in a metallic substrate. The pit patterns form digital words and can be read by shining a laser beam on the disc surface and detecting the reflected beam. The information storage capacity of a typical DVD, however, is much higher than a CD. Presently available DVDs have a variety of capacities which depend on the technology used to manufacture the discs. Single-layer technologies can be either single or double-sided with capacities of 4.7 gigabytes and 9.4 gigabytes, respectively. Dual layer technologies will soon be available which use single or double sided capacities that hold approximately 8.5 gigabytes per side. This high information storage capacity makes DVDs suitable for storing not only audio information, but also video information and large amounts of computer data as well.
DVD players have many CD player features, such as the ability to play selections in any order desired and the ability to read information from any point on the disc. However, DVDs can store information in several formats. For example, DVDs which are used to store video information, hereinafter called DVD-VIDEO discs, may use various known information compression algorithms, such as MPEG-2 for video compression/decompression. A DVD may also include high fidelity sound as well. In addition, a DVD may also store uncompressed linear pulse code modulated data streams which may have varying sample rates. Still other DVD versions, hereinafter called DVD-ROM discs, can store digital data for computer use, and the data may also be compressed on these discs.
Although DVD-ROM and DVD-VIDEO discs share compression algorithms, the data format on DVD-VIDEO discs is significantly different than the data format found on DVD-ROM discs. One important difference is that the data content on DVD-ROM is platform-specific, while DVD-VIDEO discs operate with a platform independent navigation engine for playing interactive movies. This navigation engine requires that the files on the DVD-VIDEO disc be referenced in a predetermined directory structure.
The specific navigational commands that are recognized by a DVD player are controlled by a device independent language and a set of DVD player parameters which define the current state of the DVD player. The DVD command set, including the aforementioned commands and their definitions, are published in the DVD specification. A copy of the DVD 1.0 Specification for Read-Only Disc Vol. 3, including a more detailed description of all DVD commands, may be obtained, for example, from Toshiba Corp., 1--1 Shibaura 1-Chome, Minato-ku, Tokyo 105-01 Japan.
When a user accesses the navigational commands with a pointing device, such as a mouse or trackball icon, the user manipulates the pointing icon to the desired command or button. Once the user has located the desired command, the user clicks on the button with the pointing device to select or activate the command. The user navigators currently available use linear processing to determine the coordinates of each button. The pointing icon typically falls with a range of coordinates to signify that a given button has been selected. Unfortunately, various DVD titles and programs are offering buttons that overlay one another for ease of use and esthetic appeal. Unfortunately, the current navigator systems do not recognize when such buttons lay one on top another and cause confusion to the operator in attempting to select a desired button.
For example, the program may have three buttons that display text of their presence, but lack an outline showing their respective borders. Furthermore, the several buttons may be overlain such that one of the buttons, otherwise visible had it had an active border, is invisible and hidden from the user. The user would not be able to select the desired button. Additionally, once a user moves the pointing icon directly to the desired button, if that button is behind another button in sequence, although visible to the user, and the button is selected, an inappropriate button will be selected instead.
Accordingly, a need exists for a method and system for selecting the most logical button associated with the user's actual placement of the pointing device icon on a group of buttons that overlap one another.